Name of the Mine
Platosa mine.

Location  
The mine is located 5 km north of Bermejillo, Durango state, Mexico.

Mine Owner/s  
Excellon Resources, through its wholly owned subsidiary Minera Excellon de Mexico.

Brief Description  
Platosa is one of the highest-grade silver mines in Mexico.

The deposit comprises a series of high-grade carbonate-replacement deposits occurring as mantos.

Brief History  
The mine started production in June 2005. Early in the fourth quarter of 2022 production ceased at the mine.

Primary Metals/Minerals  
Silver, lead and zinc.

Secondary Metals/Minerals  
None stated.

Geology/Mineralisation  
The Platosa mine is situated in the Sierra Bermejillo, a north-west-trending anticline-syncline pair developed in Mesozoic sedimentary rocks.

Excellon says in the ‘Technical report for the Platosa polymetallic (silver, lead and zinc) mine, Mexico’ published in June 2021 that the mine is underlain by folded and faulted Mesozoic sedimentary rocks, locally intruded by dykes and sills of Laramide age.

The principal fault system in the property area is the Platosa Structural Zone (PSZ), a 250- to 1 500-m-wide north-west-trending zone of fracturing and shearing that traverses the eastern margin of the Sierra Bermejillo. The PSZ includes a series of fault plains that strike north-north-westerly and dip steeply east; it has been mapped along strike for 5 km north-west and south-east of the Platosa mine.

The Platosa mine targets polymetallic (silver, lead and zinc) mineralisation occurring as shallow to steeply dipping bodies of massive carbonate replacement deposits or mantos. The main silver-, lead- and zinc-bearing minerals are galena, sphalerite, acanthite and lesser proustite. The mantos dip in accordance with the stratigraphy towards the east where a series of late extensional features extend the mineralisation to depths ranging from 60 m on the west side of the mine to about 320 m on the east.

Three large-scale deformation events and the onset of a Tertiary magmatic event created favourable ground preparation and a magmatic source for mineralising fluids. The most significant mantos at Platosa are the 623, NE-1 and NE-1 south mantos, which are currently being mined and are open for expansion.

Reserves  
None stated.

Resources  
Total measured and indicated resources as at March 31, 2021, were estimated at 317 000 t grading 485 g/t silver, 5.3% lead and 5.5% zinc. Inferred resources were estimated 42 000 t grading 749 g/t silver, 4.3% lead and 5.4% zinc.

Mining Method  
The primary mining method has historically been a modified room-and-pillar, with the top of the manto being accessed first. During late 2019 to early 2020 the mining method transitioned from cut-and-fill/drift-and-fill to an overhand cut-and-bench method to improve the overall mining cycle efficiency.

Major Infrastructure/Equipment  
The mine includes underground haul trucks, an over-the-road dump truck, a wheel loader, and a jaw crusher.

Ventilation at Platosa is provided by a pull system. The mine also features water pumping stations.

Prospects  
Excellon started winding down operations at Platosa during the third quarter of 2022, as the operation transitioned to care and maintenance.

Contact Details
Excellon Resources
Tel +1 416 364 1130
Email info@excellonresources.com

Sources
Excellon Resources. Website: https://excellonresources.com/.
Excellon Resources. Technical report for the Platosa polymetallic (silver, lead and zinc mine) mine, Mexico (June 17, 2021).
Excellon Resources. Excellon Reports Q4 and Annual 2021 Financial Results (March 31, 2022).